This invention relates to circuitry for driving or energizing gas display panels, and more specifically relates to driving circuits for panels of the type disclosed in U.S. Pat. No. 4,080,597, issued Mar. 21, 1978.
U.S. Pat. No. 4,080,597 discloses an apparatus for providing a visual information screen of the type formed from a plurality of gas cells wherein electrical voltages are capacitively coupled to selected gas cells to cause gas ignition and subsequent light emission. The patent describes a gas display panel utilizing a single plane of parallel spaced conductors to ignite gas in channels perpendicularly aligned with respect to the conductors and capacitively isolated therefrom. A "gas cell" is defined by the region within a channel between two parallel conductors, and the magnitude of the voltage potentials on the respective adjacent conductors determines whether or not a "gas cell" becomes ignited or extinguished. The voltage utilized for operating a gas display panel of this type is derived preferably from a single voltage source, typically in the range of 200-250 volts, and the driver circuits utilized for controlling such voltage are preferably relatively fast-operating, high voltage switching circuits. Since the gas display panel is typically utilized in conjunction with digital equipment operating at typical digital equipment logic voltage levels (0-5 volts DC), it is preferable that the driver circuit for such a gas display panel be responsive to such digital logic low voltage signals.
U.S. Pat. No. 4,176,298, issued Nov. 27, 1979, and entitled "Display Panel Apparatus and Method of Driving" discloses a sequence of voltage drive signals which is advantageously used for energizing a display panel of the general type relating to this invention. This patent teaches that the adjacent electrical conductor segments which are embedded in the gas display panel are preferably activated according to a preferred timing sequence so as to more reliably control the respective ignition and extinguishing of the "gas cells" within the panel, and discloses a repetitive timing cycle which is utilized to activate the display driver circuits, the timing cycle preferably having pulse time durations on the order of 5-10 microseconds. Such a timing sequence is readily designed by utilizing state-of-the-art circuits in digital logic design and such circuits may be utilized with the present invention.
A further example of a display panel which may be utilized with the present invention is found in copending U.S. Patent Application Ser. No. 046,706, filed June 18, 1979 and entitled "Improvement in Plasma Display Panel". Disclosed therein is a flat glass display panel having closely spaced conductor segments, wherein some conductor segments are connected together to form a plurality of conductor segments driven by a single driver circuit and other conductor segments are individually driven by a voltage driver circuit.
In the prior art the problem of coupling display panel driver circuits, which must necessarily operate in a voltage range exceeding 200 volts, with digital logic circuits operating in the 0-5 volt range has been solved by using voltage and current boosting components such as transformers. These components are typically used as power couplers to enable digital logic circuits to generate signals of sufficient drive power to control relatively higher voltage switching circuits. An example of such a prior art circuit arrangement is described more fully hereinafter; among the many disadvantages of such circuit arrangements are their significantly higher cost, higher weight and space requirements, nonuniform electrical characteristics and their propensity toward introducing spurious and destructive electrical noise signals into the system.